Model-Based Design has proven effective for developing complex cyber-physical systems, yet its workflows remain largely manual. Additionally, industrial workflows often cross tool and organizational boundaries. This paper presents an agentic MBD framework for such boundary-crossing workflows. The architecture combines the Model Context Protocol (MCP) as the agent-to-tool interface, with FMI 3.0 as a model-to-model interface. We report an initial case study in which an agent builds a battery management system faultprotection model around a supplier-provided battery pack FMU. The case study demonstrates the feasibility of using MCP and FMI as complementary interoperability boundaries for agent-driven MBD workflows and highlights the interface and verification challenges that emerge at those boundaries. The architecture is tool-neutral by design; the present work exercises it through a MATLAB® and Simulink® reference implementation.